Update ZipError to latest rust

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "zip"
-version = "0.0.7"
+version = "0.0.8"
 authors = ["Mathijs van de Nes <git@mathijs.vd-nes.nl>"]
 license = "MIT"
 repository = "https://github.com/mvdnes/zip-rs.git"

src/result.rs

@@ -2,6 +2,7 @@
 
 use std::io;
 use std::error;
+use std::fmt;
 
 /// Generic result type with ZipError as its error variant
 pub type ZipResult<T> = Result<T, ZipError>;
@@ -23,6 +24,28 @@ pub enum ZipError
     ReaderUnavailable,
 }
 
+impl ZipError
+{
+    fn detail(&self) -> ::std::string::CowString
+    {
+        use ::std::error::Error;
+        use ::std::borrow::IntoCow;
+
+        match *self
+        {
+            ZipError::Io(ref io_err) => {
+                ("Io Error: ".to_string() + io_err.description()).into_cow()
+            },
+            ZipError::InvalidZipFile(msg) | ZipError::UnsupportedZipFile(msg) => {
+                (self.description().to_string() + ": " + msg).into_cow()
+            },
+            ZipError::ReaderUnavailable => {
+                self.description().into_cow()
+            },
+        }
+    }
+}
+
 impl error::FromError<io::IoError> for ZipError
 {
     fn from_error(err: io::IoError) -> ZipError
@@ -31,6 +54,14 @@ impl error::FromError<io::IoError> for ZipError
     }
 }
 
+impl fmt::Display for ZipError
+{
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error>
+    {
+        fmt.write_str(&*self.detail())
+    }
+}
+
 impl error::Error for ZipError
 {
     fn description(&self) -> &str
@@ -44,17 +75,6 @@ impl error::Error for ZipError
         }
     }
 
-    fn detail(&self) -> Option<String>
-    {
-        match *self
-        {
-            ZipError::Io(ref io_err) => io_err.detail(),
-            ZipError::InvalidZipFile(detail) |
-            ZipError::UnsupportedZipFile(detail) => Some(detail.to_string()),
-            ZipError::ReaderUnavailable => None,
-        }
-    }
-
     fn cause(&self) -> Option<&error::Error>
     {
         match *self